"Idolatry is taking a good thing and making it an ultimate thing."
What is in our lives--if suddenly taken away--would affect us to the point that we might not want to go on living? A tough question that gets to the heart of what we organize our lives around for meaning, identity, significance, and love other than God.
Thomas Chalmers the 18th century Scottish Presbyterian pastor talks about idols and personal transformation: "There is not one personal transformation in which the heart is left without an object of ultimate beauty and joy. The heart's desire for one particular object can be conquered, but it's desire to have some object is unconquerable. The only way to dispossess the heart of an old affection is by the expulsive power of a new one."
In another wonderful sermon---which I can't link directly to---Keller talks about finding transformation and dismantling idols---through the power of Jesus Christ working in our lives. Scroll down to the sermon entitled "Christ our Life," based on a Scripture reading from Colossians 3:1-14.
It doesn't get much better than Keller.